The present invention relates generally to an apparatus for inserting a weft yarn in jet-operated looms, or more specifically to an apparatus for mounting weft yarn guiding members on a race in said jet-operated looms.
To roughly group the methods of inserting a weft yarn into a shed along the weft picking channel formed by weft guides in jet-operated weaving machines in respect of the injection nozzles in use, there are two types of nozzle arrangements. According to one type, a weft yarn is picked through a shed solely by a fluid jet issued from a main nozzle which is provided at one end of said weft guiding channel; and, according to the other type, a weft yarn is inserted through the channel by jet fluid issued from a plurality of auxiliary nozzles spaced along said channel, as well as from a main nozzle. The latter method, on which the apparatus of the present invention operates, may be further classified into two concrete forms or types in terms of the structure of the weft guide members, as follows:
According to a structure of the first type as represented by U.S. Pat. No. 3,139,118, some of those weft guides which form the channel for picking the weft are formed with a hollow passage therein, respectively, into which fluid under pressure is supplied so that such fluid is injected into said weft guiding channel from a plurality of apertures formed on the peripheries of said hollow guides and in such a way as to surround the channel.
According to the second type as disclosed by U.S. Pat. No. 4,244,402, the weft inserting apparatus thereof comprises a reed which carries the picked weft to the cloth-fell for beat-up, weft guides forming the weft picking channel, and a plurality of auxiliary nozzles spaced along said channel, said auxiliary nozzles being adapted to allow weft carrying medium to be issued therefrom into said channel.
In the former type, in which fluid under pressure is issued from apertures on the peripheries of weft guide members forming part of the guide channel, the fluid thus issued may be controlled immediately after such release by the guide members located on the downstream side, and thus rectified into a flow of imaginary cylindrical shape. However, a drawback of this type is the difficulty and therefore costliness of manufacture.
On the other hand, the second type in which the auxiliary nozzles thereof are located relatively far, as compared with the first type, from the guide channel due to the manner of mounting thereof on the slay, makes it more difficult to properly control the flight of the weft in the guide channel by the fluid from such auxiliary nozzles, but the arrangement is easy to manufacture and is therefore less costly. In the event any weft guides of the latter type must be replaced with new ones due to possible damages thereto, however, the old ones must be removed from the slay independently of the auxiliary nozzles and then new ones must be fixedly mounted on the slay, which means it is difficult to secure accuracy in positioning the new weft guides in relation to the auxiliary nozzles after such replacement. In addition to this drawback, even damage to just part of the guides will call for replacement of all guides as a whole, thus requiring higher cost for maintenance of the weft inserting apparatus.